The present invention relates to positional alignment systems, and more particularly, to an optical system for determining the relative position and center line collineation of hole patterns and for measuring the movement of plane surfaces.
In many manufacturing activities such as the complex act of building of large aircraft assembly fixtures or the simple act of drilling holes in a flat pattern part there is a need to measure the relative mismatch of two hole centerlines one with respect to another. Thus, in the latter application after the hole pattern has been drilled it is often required to know how precisely the hole positions in the part match the hole positions in a drill jig from which it was fabricated. One method that is typically used to determine mismatch, is fitting the largest pin that will pass through both the hole in the drill jig and the hole in the part. This technique has several drawbacks. First, it does not define the true location of one hole with respect to another. Second, undersize pins introduce a number of geometric errors into the measurement between holes implying centerline collineation that in fact may not exist. Third, this technique is a trail and error process of selecting the pin that fits from a range of pins which is both time consuming and imprecise since the quality of the pin fit selection can vary with the skill of the technician. Finally, if more than one pin is inserted, they can "load" up or distort the hole in the part and affect the measurement.